Rear Window Defogger
WARNING: This page is about a different car, the 2002 Jeep Liberty. However, it is still accessible from the selected car via links, so may be relevant.
The Body Control Module reads the Rear Window Defogger Switch and turns on the rear window defogger relay to defrost the rear glass. The first time in an ignition cycle that the driver presses the defogger button, the BCM will turn on the relay for 10 minutes. The second and subsequent times, the BCM will turn on the relay for 5 minutes. If the ignition is turned off, the BCM will turn the rear window defogger relay off.